Messi Biology states that magnesium carbonate is an important component of electronic ceramic materials, playing a crucial role in the preparation and performance optimization of these ceramics. It primarily serves as a magnesium source, used to adjust the physical, chemical, and electrical properties of ceramic materials. It has widespread applications, especially in dielectric ceramics, semiconductor ceramics, and functional ceramics. The following are the main functions of magnesium carbonate in electronic ceramics:
- As a Sintering Aid, Lowering the Sintering TemperatureIn the sintering process of ceramic materials, magnesium carbonate can promote the densification of the material and lower the sintering temperature. For example, in the preparation of barium titanate (BaTiO₃) based ceramics, magnesium carbonate can promote grain growth and improve the dielectric properties of the material. In addition, it can reduce grain boundary energy, increase the sintering activity of ceramic materials, and lower the sintering temperature by 50-200°C, thereby reducing energy consumption.
- Improving the Mechanical Strength and Density of CeramicsMagnesium carbonate decomposes into magnesium oxide (MgO) at high temperatures. Magnesium oxide has good sintering characteristics, which can increase the density of ceramics, reduce porosity, and thus enhance the bending strength, hardness, and toughness of the ceramic. This is very important for electronic ceramics that require high mechanical properties (such as piezoelectric ceramics, ceramic substrates, etc.).
- Adjusting the Dielectric Properties of CeramicsIn electronic ceramics, dielectric constant and dielectric loss are important indicators. Magnesium carbonate can adjust these parameters in the following ways:
- Increasing Dielectric Constant: In barium titanate-based ceramics, an appropriate amount of magnesium carbonate can promote grain growth, increase the dielectric constant, and give the material better electrical performance in high-frequency environments.
- Reducing Dielectric Loss: Excessive impurities or defects can lead to increased dielectric loss. High-purity magnesium carbonate can reduce defects at grain boundaries, lower dielectric loss, and improve the working stability of electronic components.
- Promoting Uniform Grain Growth and Optimizing MicrostructureThe performance of electronic ceramics is affected by grain size and distribution. Magnesium carbonate can act as a grain growth regulator, promoting the formation of a uniform and fine grain structure, preventing abnormal grain growth, and improving the stability of the ceramic.
- In multilayer ceramic capacitors (MLCCs), the addition of magnesium carbonate can make the particle distribution of the dielectric layer uniform, improving the reliability of the product.
- In NTC thermistor ceramics, a uniform grain structure helps to improve the thermistor characteristics, making the temperature response more stable.
- Lowering the Coefficient of Thermal Expansion and Improving Thermal StabilityMagnesium carbonate decomposes into magnesium oxide at high temperatures. The addition of magnesium oxide can lower the coefficient of thermal expansion of ceramic materials, improving the stability of the material in high-temperature environments. For electronic ceramics that need to work at high temperatures (such as high-frequency ceramics, microwave dielectric ceramics), the role of magnesium carbonate is particularly important.
- Influencing Electrical Conductivity and Improving Electrical PerformanceIn semiconductor ceramics (such as PTC thermistors, NTC thermistor ceramics), magnesium carbonate can affect the carrier concentration of the material, thereby adjusting its electrical conductivity. For example, in nickel manganite (NiMn₂O₄) based NTC ceramics, the doping of magnesium carbonate can adjust the resistance temperature coefficient of the material, improving the sensitivity and stability of the temperature sensor.
- Acting as an Inhibitor to Prevent Grain Boundary ReactionsIn some electronic ceramic systems, magnesium carbonate can act as an inhibitor to prevent the formation of harmful phases at the grain boundaries, avoiding the degradation of material performance. For example, in nickel aluminate (NiAl₂O₄) based ceramics, magnesium carbonate can inhibit the diffusion of NiO, thereby maintaining the insulation of the ceramic.